"I'm stunned and heartbroken to hear the devastating news of Ugly Betty creator, Silvio Horta's death. His talent and creativity brought me and so many others such joy & light," Ferrera, who portrayed the title character on the series said on Instagram Tuesday alongside a photo of herself and Horta at the Golden Globe Awards.
"I'm thinking of his family and loved ones who must be in so much pain right now - and of the whole Ugly Betty family who feel this loss so deeply," the actress continued.
Williams, who portrayed Wilhelmina Slater on the comedy, uploaded a selfie of herself with Horta to Instagram.
"Still in shock after hearing the tragic news of our #uglybetty creator #silviohorta. His creativity and passion will be missed by so many of us that worked with him. May he Rest In Peace," she said.
"I will be forever indebted to this sweet, brilliant man," Urie, who appeared as Marc St. James on Ugly Betty said on Twitter.
"Silvio and I used to stay up late and laugh until our sides hurt - and complain to one another about life. He wrote the finest scenes, for all of us - crafted the wonderfully flawed being I've ever had the privilege to embody. I'm empty right now...," Eric Mabius, who starred as Daniel Meade on the show, said on Twitter.
Horta was found dead of an apparent suicide at the age of 45 inside a Miami hotel room on Tuesday.
Horta also wrote the screenplay for horror film Urban Legend, television movie The Curse of the Fuentes Women and created sci-fi series The Chronicle and Jake 2.0.
Ugly Betty ran for four seasons on ABC from 2006 to 2010.